5396713-BIM-C-0319
Johnson Controls Ducted Systems
3
SECTION III: UNIT INSTALLATION
LOCATION
Access for servicing is an important factor in the location of any furnace.
Provide a minimum of 24” (61 cm) in front of the furnace for access to
the heating elements and controls. This access may be provided by a
closet door or by locating the furnace 24” (61 cm) from a facing wall or
partition.
FURNACE CLEARANCE
This furnace is approved for zero (0) inch clearance to combustible
material on all or any part of the furnace exterior and the inlet or outlet
duct work except as stated below.
For furnaces installed in upflow application, there must be a minimum
of 1” (2.54 cm) clearance from the bare surface of the outlet duct work
for a distance of 3 feet (91.4 cm) from the supply air opening. This
requirement is met if the duct is wrapped with an insulating material at
least 1” thick and having an R-value of at least R-4.
RETURN AIR
In order for the furnace to work properly, a closet or alcove must have a
certain total free area opening for return air.
For Heating Only Furnace
Minimum 200 sq. in (1290 sq. cm) free area opening. Use any return
Grille with minimum 200 sq. in. free opening.
For up to 4 Ton AC & HP Applications (Standard Blower)
Minimum 250 sq. in. (1613 sq. cm) free area opening. The standard
blower assembly supplied with the furnace is capable of handling up 4
Ton AC applications. Use any return grille with minimum 250 sq. in.
(1613 sq. cm) free area opening.
For 5 Ton AC Applications (Accessory Blower)
Minimum 350 sq. in (2129 sq. cm) free area opening. Use 5 Ton AC
blower accessory 3500-7901/A. Use any return grille with a minimum
350 sq. in. (2129 sq. cm) free area opening.
Location
For downflow applications, the return air opening can be located in a
closet front door, or in a sidewall above the furnace casing, or in a lou-
vered door on the furnace. If opening for the return air is located in the
floor, side walls or closet door anywhere below furnace casing height, 6
inches minimum clearance must be provided on the furnace side where
return is located to provide for proper air flow.
For Upflow installations, a closet that is 32 inches wide by 30 inches
deep with a 30-inch wide door is necessary. This is not required if there
is a return grille installed below furnace.
The return air opening can be located in a closet front door or a side-
wall above the furnace casing, or in a louvered door on the furnace. If
opening for the return air is located in the floor, side walls or closet
door anywhere below furnace casing height, 6” (15.2 cm) minimum
clearance must be provided on the furnace side where return is
located to provide for proper air flow. See Figure 2. The 6” (15.2 cm)
minimum clearance is not required if there is a return grille installed
above the furnace height. This return grille cannot start more than
three feet above the furnace height. If the louvers in the closet door
have as much air flow area as the EB louvered furnace door, only 1”
clearance is required.
When installing furnace in a separate closet or room which is accessi-
ble only through an outside door, a minimum of 200 in
2
(1290 cm
2
) free
opening for return air must be provided. The supply and return air must
be ducted, securely attached and be sealed to the furnace casing if
there are grilles in the outside door to the closet. Openings where ducts
pass through walls, the floor or the ceiling must be sealed to prevent air
leakage into or from closet and the living area.
Provisions shall be made to permit the return of circulating air from all
rooms and living spaces, except the bathroom(s) to the circulating air
supply inlet of the furnace. Failure to comply may cause improper heat-
ing and may cause the furnace to cycle on the limit.
DUCT SYSTEM DESIGN
Electric furnace is designed to operate at a given static pressure.
In order to assure proper air flow through the furnace, the distribution
system must be designed so that the static pressure external to the fur-
nace does not exceed the static pressure rating shown on the furnace
rating plate.
The number, size and placement of registers should be such that even
distribution of heat is provided throughout the home.
FIGURE 2:
Alcove & Closet Clearances
FIGURE 3:
Upflow Closet Clearances
23” MIN.
20”
20”
24” MIN.
There must be at least
2 feet of space available
in front of furnace for
servicing the furnace
when necessary.
A 6 inch clearance is
required if the space
between furnace and
enclosure is used for
return air.
A0844-001
30”
32”
30”
WIDE DOOR
CLOSET
25-1/2”
OPENING WIDTH
Return air
pass through
frame width.
1-5/8”
2-3/8
MIN.,
MAX.
A0877-001
NOTE:
Minimum required square
inch opening dictates the
height of the return air
opening as discussed
earlier in the section.
